1. Field of the Invention
The present invention relates to a method for preparing an organic light-emitting diode (OLED) and, more particularly, to a method for preparing an OLED by an imprinting process, in which a large area light-emitting layer can be prepared rapidly.
2. Description of Related Art
Organic light-emitting diodes (OLED) have great potential as a next generation lighting and displaying devices for being ultra-thin (1 mm or less) in thickness, high brightness, wide viewing angle (more than 170°), no backlight requirement, rapid response, high resolution, low heat generation, low energy consumption, and applied as flexible electronics. Hence, the OLED has been widely studied in academic researches and relevant industries. As shown in FIG. 1, the structure of the conventional OLED comprises: a substrate 101, an anode 102, a hole injection/transport layer 103, a light-emitting layer 104, an electron injection/transport layer 105, and a cathode 106. The light-emitting layer 104 is located between the hole injection/transport layer 103 and the electron injection/transport layer 105, and the function of the light-emitting layer 104 is used to generate or control the combination of holes and electrons which resulting in emissions. When the light-emitting layer 104 is composed of all emissionable red, green, and blue organic materials, an OLED with full color can be obtained.
Currently, the light-emitting layer of the OLED can be prepared through a vacuum evaporation process, a spin coating process, or an injection printing process. However, these processes still have some disadvantages described as following.
When the vacuum evaporation process is performed, vacuum equipment has to be used to generate a vacuum condition. However, the vacuum equipment is very expensive, which results in the increase of the production cost. Also, it is difficult to prepare large-area organic layers by using the vacuum evaporation process. Although the large-area organic layers can be formed in a low-cost way through the spin coating process, the spin coating process can only be performed on a substrate with a plane surface. Hence, the spin coating process cannot be used on the substrate with curved surfaces, or the substrate with patterns. In addition, a patterned light-emitting layer cannot be easily obtained through the spin coating process.
In order to reduce the production cost of the OLED, it is desirable to provide a method for preparing a light-emitting layer of an OLED in a rapid and inexpensive way, and further preparing a light-emitting layer with large area and full color.